Web tension control mechanism



W. F. HUCK -WEB TENSION CONTROL MECHANISM Apri 21, 1959 F il ed April10, 1957 2 Sheets-Sheet 1 INVENTOR 3 'AOEY April 21, 1959 w. F. HUCK wasTENSION CONTROL MECHANISM Filed April 10, 1957 2 Sheets-Sheet 2 INVENTOR/V/u/AM F Huck VMFW ATTORNEY MmL- i xim u I lr/l lllrlllllll UnitedStates Patent WEB TENSION CONTROL MECHANISM William F. Huck, ForestHills, N.Y., assignor to Huck Company, New York, N.Y., a partnershipApplication April 10, 1957, Serial No. 651,875

7 Claims. (Cl. 2712.3)

This invention relates in general to web control devices, and moreparticularly to devices for closely controlling the tension incontinuous webs undergoing a variety of operations.

In certain arts where operations are carried out on a continuous movingweb of cloth, paper or the like, it is important that the tension of themoving web be adjustable at certain points without respect to itstension at other points, and at the same time it is desirable to preventany material change of web length between positions where the desiredoperations are being carried out upon the web.

It is an object of this invention to provide a web tension controldevice which will automatically maintain the tension of acontinuousmoving web substantially constant in one region within certainpredetermined limits, and independent of any changes occurring inanother region.

It is another object of this invention to provide a tension controldevice for use with a moving web of paper, cloth and the like, in whichthe Web length between fixed positions is not materially altered byaction of the web tension adjustment device.

It is another object of this invention to provide a Web tension controlmechanism which is simple and economical of construction and which maybe used for continuous webs of cloth, paper, metal or the like.

Another object of this invention is. to provide a web tension controlmechanism which acts quickly and auto matically to compensate forundesired changes in tension of the web, so as to maintain the webtension within certain predetermined limits.

Briefly, the invention provides a pair of web carrying roller carriages,both movable back and forth in the direction of web travel, the webbeing wrapped in S or serpentine fashion about the rollers of onecarriage, and then passed about a roller of the other carriage. Thefirst carriage, when moved by a change in the entering web tension,actuates a servomechanism to move the second carriage in the samedirection. A constant tension device controlled by the first carriagepreserves the desired tension on the entering Web, independent ofchanges in tension of the departing web, because the effectiveamplification of the servo action isolates the first carriage fromreactions due to tension effects on the second carriage. The above isaccomplished without any appreciable effect on the web lengthdistributed about the frame rollers.

The foregoing and other objects and advantages will become apparent whenthe following specification is read inconjunction with the attacheddrawings, in which:

t Figure 1 is a side elevation of a web tension control device embodyingthis invention.

Figure 2 is a horizontal offset sectional view taken along the planes2-2 of the device illustrated in Figure 1.

Figure 3 is an offset sectional view taken along the planes 33 of thedevice illustrated in Figure 1.

Figure 4 is a sectional view of the fluid pressure servo controlmechanism utilized in the device illustrated in Figure 1.

2,883,186 Patented Apr. 21, 1959 Although the following describes theinvention as used with a moving continuous paper web through a printingpress, it is obvious that the invention may be used for maintainingproper tension in continuous web of cloth, metal, or the like in whichvarious operations other than printing are to be performed upon themoving continuous web. Referring now to the drawings, and Figure 1particularly, a continuous web 10 is illustrated as entering the controlmechanism at the position R, in a horizontal plane. The web tensioncontrol mechanism comprises a first or lower section and a second orupper section. The web 10 entering the mechanism at the position Renters the lower section first. The first or lower section includes avariable tension compensator which may be similar to the web tensioncontrol mechanism described and illustrated in the U.S. patentapplication of W. F. Huck, filed November 16, 1953, S.N. 392,292, nowPatent No. 2,787,463, and includes two rollers 12 and 14 around whichthe web 10 is wound in a serpentine fashion, then led from roller 14 toan idler roller 16 and then directed upwardly in a substantiallyvertical direction to the second or upper section of the web tensioncontrol mechanism.

The rollers 12, 14 and the idler roller 16 are mounted in verticalcarriage frames 18 and 20 (the latter shown in Fig. 3) which arearranged to slide freely along the horizontal bars 22 and 24 by means ofsleeve bearings 26 and 28. The roller 12 is shown as driven by a drivepulley 30 acting through a V-belt 32 passing around an adjustable pulley31 mounted upon the shaft carrying the roller 12. The vertical carriageframes 18 and 20 canying the rollers 12, 14 and 16 and forming a compactmovable carriage, are urged to the right as by an adjustable springmechanism including a coil spring 34 connected to the carriage frame 18at a projection 36 and to a member 38 of the machine frame by means ofan eye bolt 40 passing through a projection 42 of the frame 38, andadjusted by means of a nut 44. Obviously, other equivalent means forurging carriage frames 18 and 20 to the right may be substituted; forexample, an air or fluid cylinder arrangement. Moreover, so far as theinstant invention is concerned, the tension controlling V-belt drive maybe replaced by equivalent mechanism of other forms.

The second or upper section of the complete web tension control meanswill now be described. Situated above and offset to the right of thelower section support bars 22 and 24 are two parallel upper sectionhorizontal support bars 46 and 48. A pair of vertical carriage members50 and 52 having sleeve bearings 54 and. 56, respectively, are arrangedfor sliding movement upon the sup port bars 46 and 48. An idler roller58 is carried by the upper carriage members 50 and 52. The verticaltraveling web 10 leaving the idler roller 16 on the lower section ofthis device is passed around the upper section idler roller 58 andthence out of the device in a horizontal plane to the position S asillustrated in Figure 1.

The upper section carriage member 50 is movably connected to the lowersection carriage frame 18 by means of a link 60, and a fluid pressurecylinder control rod 62. A fluid pressure cylinder 64 is rigidlyfastened to the carriage member 50 by means of bolts 66, and receivesthe control rod 62 in a manner disclosed in detail below. The cylinder64 is provided with a piston 68 and piston rod 70. As seen in Figure lthe piston rod 70 is clamped rigidly to the upper section support bar 46by means of the clamping member 72, so that the piston 68 and piston rod70 are incapable of movement relative to the support bar 46.

The fluid pressure cylinder 64 and its associated control mechanism aredisclosed in detail in Figure 4. The cylinder 64 is provided with avalve chamber 74 to which is connected a conduit 76 from a source offluid pressure; for example, compressed air. Within the valve chamber 74is positioned one end of the cylinder control rod 62 carrying two spacedvalve members 78 and 80 for covering or uncovering valve ports 82 and84, respectively, connecting the valve chamber 74 with the interior ofthe cylinder 6.4. The valve ports 82 and 84 are so positioned that thepiston 68 is always located between them under all conditions ofoperation.

A pair of L-shaped brackets 86 and 88 are clamped rigidly to the uppersection support bars 46 and 48 to provide a support for a cross barmember 90. One leg of eachof the L-shaped brackets is provided with acircular opening 92 and 94, respectively, into which are fitted sleevebearings 96 and 98, so that the cross bar 90 can rotate freely about itsaxis. Depending bars 102 and 104 are rigidly secured near the ends ofthe cross bar 90 by means of bolts 106. Pivotally secured to the lowerends of the depending bars 102 and 104 are respective link members 108and 110, the opposite ends of the link members being pivotally connectedto the upper section carriage members 50 and 52 respectively by means ofbolts 112 and 114.

, In the operation of this web tension control device, the verticalframes 18 and 20 of the first or lower section are urged to the right(Fig. 1) by the adjustable spring 34, which force is opposed by thetensional force in the V- belt 32 which drives the roller 12. Inaddition, the vertical carriage frames 13 and 20 are urged by the web inthe leftward direction to a degree depending on whether the web ismoving momentarily too fast or too slowly through the Web tensionmechanism. If, in operation, there is an increase in tension of the web10 traveling through this device, the lower section vertical carriageframes 18 and 20 would be displaced to the left (Fig. 1). This motiondisplaces the connecting link 60 (which connects the upper and lowersections) and the air cylinder control rod 62 also to the left. Thismovement of the control rod exposes the valve port 32 (Fig. 4) therebypermitting pressure fluid to enter the cylinder 64. Since the piston 68and piston rod 74) are held immovable by the clamping bar 72, 'thecylinder 64 itself will be forced to the left (Fig. 1). This motion tothe left of the cylinder 64 will continue until a position is reachedwhere the valve 78 covers the valve port 82 (Fig. 4). The cylinder 64then comes to rest until the control rod 62 is moved again because ofmovement of the lower section vertical carriage frames 18 and 20. Sincethe cylinder 64 is bolted securely to the upper section carriage frame50, any movement imparted to the cylinder causes movement also of thecarriage frame 50. Thus the movement of the lower section to the leftcauses the cylinder 64 and upper section carriage frame 50 to move tothe left an amount identical to the movement of the control rod 62.Hence, the idler roller 58 mounted in the upper section carriage members50 and 52 is moved to the left an amount identical to the movement oflower section vertical carriage frames 18 and 2t), preserving the weblength constant and the section of web between rollers 16 and 58vertical.

The above described arrangement and operation ensures that motion of thefirst or lower section carriage frames 18 and 20 will be followedaccurately by upper section carriage frame 50. Therefore the first orlower section carriage frame and the second or upper section carriageframe always have the same relative position, thereby maintaining asubstantially constant web length between the entering point R and theexit point S to affect the web tension at entering point R. The webtension of entering point R is held constant within certainpredetermined limits by the action of this web tension on rol me ni m-Although the invention has been described and illus- {rated ascomprising an upper and lower section, it is ob- 4 vious that changesmay be made in the relative locations of the two sections withoutdeparting from the spirit of the invention. Although a variable speedV-belt drive has been described for driving the feed roller in the firstor lower section it is obvious that equally desirable results can beobtained by the use of sensitive hydraulic or electrically controlleddrives. In addition, the lower or first section biasing spring 34 may bereplaced by a piston and cylinder arrangement utilizing adjustable fluidpressure control, or other equivalents.

Figure 1 shows the device arranged for a web which enters at R anddeparts at S, travelling from left to right. It is obvious that the samedevice can be arranged with the web travelling in the oppositedirection, or from S to R. In either case, the constant-tension sectionof the web will lie, in Figure 1, to the left of the device itself.

The invention has been described above in connection with a singlepreferred form given by way of illustration;

however, the details of the equipment used in carrying tent that theyfall within the terms of the appended,

claims.

What is claimed is:

1. In a web tension control mechanism, the combination comprising afirst section and a second section, said first section including atleast a first rotatably and movably mounted roller around which the webis passed, said roller being so mounted as to move in a lateraldirection an amount proportional to the tension of the web passingaround said roller, said second section being spaced from said firstsection and including an idler roller around which the web is passed,servo mechanism actuated by the lateral movement of said first rollerfor moving said idler roller an equal amount in the same direction assaid first roller, whereby the web length between said rollers remainssubstantially constant regardless of web ten sion, and means forregulating the web tension in one of said sections.

2. In a web tension control mechanism, the combina: tion comprising afirst section and a second section, said first section including aslidably mounted carriage carrying a driven roller around which the webis passed, said carriage being biased for movement in one direction andsubject to movement in response to changes in web tension, said secondsection being spaced laterally of the web travel direction from saidfirst section and including a slidably mounted carriage carrying anidler roller around which the web is passed, and power means, controlledby the movement of said first carriage for moving said second carriagean equal amount and in the same. direction as said first carriagewhereby the. web length between said rollers remains substantiallyconstant regardless of web tension.

3. In a web tension control mechanism, the combine tion comprising afirst section and a second section spaced therefrom, said first sectionincluding a slidably mounted carriage carrying rollers around which theweb is wound in serpentine fashion, said carriage being biased in onedirection and subject to movement in response to changes in web tension,said second section including a slidably mounted carriage carrying anidler roller around which the web is passed from said first section,control means linking said two sections, and power means actuated bysaid control means for moving said second carriage an equal amount andin the same direction as said first carriage whereby the web lengthbetween said sections remains substantially constant regardless of webtension.

4. The combination as set forth in claim 3, in which the power means tomove the second carriage includes a. fluid cylinder connected to saidsecond carriage.

5. The combination as set forth in claim 3, in which;

5 the two sections are spaced apart in two directions perpendicular toeach other.

6. A web tension control mechanism comprising a first section and asecond section vertically spaced therefrom, said first section includinga slidably mounted carriage, a plurality of rollers carried by saidcarriage and around which the web is passed in serpentine fashion, meansfor biasing said carriage in a direction to oppose the web tension, saidsecond section including a carriage slidably mounted for movementparallel to said first mentioned carriage, said second carriage havingmounted thereon an idler roller around which the web is passed afterleaving said first section, the web path between said carriages beingperpendicular to the direction of carriage movements, control meanslinking said two sections, power means connected to said second carriageand controlled by said control means to move said second carriage anamount equal to and in the same direction as said first carriage inresponse to changes in web tension, where by the web length between saidsections remains substantially constant regardless of changes in webtension, and a tension control connected to one of the rollers of saidfirst section.

7. The combination as set forth in claim 6, in which the power means tomove the second carriage includes a fluid pressure cylinder mounted uponsaid second men: tioned carriage.

No references cited.

